Preparation of 4-alkylated steroid compounds



United States Patent 3,210,342 PREPARATION OF 4-ALKYLATED STEROIDCOMPOUNDS Robert P. Graber, Minneapolis, and Susumu Nakanishi,

3,210,342 Patented Oct. 5, 1965 chemical and/or microbiologicalconversion to the antiinflammatory corticoid hormones, for example, byintroduction of oxygen into position 11 of the molecule by fermentationwith known microorganisms to provide an ll-hydroxy compound in which thell-hydroxy group 5:522:5 g f fi to General Mlus a may be furtheroxidized chemically to a ketone group. No Drawing Filed June 4, 19 sN0h285253 The aforementioned copending application describes 14 Cl i(Cl, 260-23955) one method of preparation of the 4-alklated products. It

has now been discovered that such product may be pre- This inventionrelates to a novel method of preparing 0 pared in high overall yield bya difierent process through 4-alkylated steroid compounds and to novelintermediates different intermediates. in the reaction sequence and inparticular to 4-monoalkyl It is therefore an object of this invention toprovide and 4,4-dialkyl steroid compounds. Illustrative of these :anovel method of preparing biologically active 4-alkylated final productsare 4,60,16a-tri1nethyl-5-pregnene-l7a-olsteroid compounds. 3,20-dioneand the acyl derivates thereof and 4,4,6,l6oc 15 It is also an object ofthis invention to provide novel tetramethyl-S-pregnene-17u-ol-3,20-dioneand the acyl intermediates in the preparation of Such 4-alliylatedderivatives thereof. products.

The 4-alkylated products are physiologically active and Briefly theinvention consists in the conversion of a are further described incommonly assigned copending 6,16-dialkyl-pregnane 3B,5u,l7a,20-tetro1 to17a,20'-ketal US. application Serial No. 245,380, filed December 18, 20form which is then xidized to the corresponding 3-keto- 1962, by S.Nakanishi. These 4-alkylated compounds, in 511-01 and dehydrated to theA -3-keto derivative. This particular the 4,4,6,l6-tetraalkyl-5-pregnenesteroids, are compound is then alkylated with an alkyl halide toproprogrestationally active and thus are of clinical value forvideeither the 4-monoalkyl or 4,4-dialkyl product which the preventionof habitual or threatened abortion, the is then hydrolyzed under acidconditions and oxidized to treatment of dysmennorhoes, pre-menstrualtension, as the final product, either a4,6,l6-trialky-l-l7a-hydroxyovulation suppressing agents and other sexcylic regula- 3,20-di0fle a y Y Q Y tory purposes. zdione. If desired,the 17-hydroxy group may then be In addition to their usefulness inthemselves as highly acylated to provide the corresponding 17-acyloxycomactive progestational horomones, these 4-alkylated com- P und. poundsare valuable intermediates in the preparation of The reaction sequencecan but be illustrated by means other steroids. The compounds are ofgreat value for the of the following sequence:

CH3 OH; H HJJO CH H C H o 2 --0H -o ona --R --R H30 H30 I Ed R no 1'2(I313: Ha HO-O CH Hdo CH H3O i H3O I R 3 "R I. 3 H30 1 1130 I Ho R [III][IV] [VIII (11)] m In the foregoing reaction sequence, R is an alkylgroup raving from 1 to 8 carbon atoms and both R groups in he 6 and 16position may be the same or difierent alkyl roups, R is an alkyl grouphaving from 1 to 8 carbon toms, and R is selected from the groupconsisting of lkyl, cycloalkyl, aralkyl and alkoxyaralkyl groups in [VII((2) the aryl group is generally phenyl. 70 alkyl groups of R and R aremethyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl,heptyl, and octyl. Illustrative of the ester groups in the 17-positlonare acetate, caproate, propionate, cyclopentyl propionate, phenylpropionate, p-propoxyphenyl propionate, p-hexoxyphenyl Illustrative ofthe which the alkyl group has from 1 to 12 carbon atoms and 75propionate and p-dodecoxyphenyl propionate.

The intermediates provided in the reaction sequence 'may be illustratedby the following formulae:

B 1 where A is selected from the group consisting of H 0 CH3 HO i Ho REd R 0H, CH3

1': B it;

and

R R R and B is selected from the group consisting of CH CH and R and Rare alkyl groups having from 1 to 8 carbon atoms.

I The starting material for the present invention is a6,8,16uadialkyl-pregnanefiju,17u,20-tetrol, which may be represented bythe formula where R is an alkyl group having from 1 to 8 carbon atoms.The preparation of this starting material is disclosed in my copendingapplication with M. B. Meyers, U.S. Serial No. 122,092 filed July 6,1961, now US. Patent 3,123,600, the disclosure of which is incorporatedherein by reference. As disclosed therein, the tetrol product may beprepared from 16-dehydropregnenolone acetate or the 3-alcoho1. Thepreparation proceeds by Grignard alkylation and in situ enol acetylationof the 16-dehydropregnenolone acetate to the 16a-alkyl-5,17(20)-pregnadien-3,20-diol diacetate. Epoxidation then provides the5,6:17a,20-dioxido-3,ZO-diacetates which on alkaline hydrolysis producethe 5,6-oxido-16ot-alkylpregnan-313,17a-diol-20-ones which are thenacetylated to the 3B-acetates. Acid-catalyzed scission then atfords thetetrolone, 16cc alkylpregnan-3B,5a,6fi,17a-tetrol-20-one which uponreclosure of the trans 5,6-diol system provides the 5a,6u oxido16a-alky1pregnan-3fl,17a-diol-20-one. Reduction with sodium borohydrideaffords the 5a,6aoxido-3fi,l7a,20-triol and Grignard opening of theoxide grouping establishes the 6fi-alkyl in6fi,16ot-dialkylpregnan-3B,5a,17oc,20-tetrol, the starting material forthe present invention.

As previously indicated, the starting material for the present inventionis then converted to the 1704, 20-ketal form. This is accomplished by anacid catalyzed reaction, i.e., hydrochloric acid, of6B,16u-dialkylpregnan-3(3,504, 17a,20-tetrol with acetone to furnish the17a,20-isopropylidenedioxy derivative by simply boiling the reactionmixture for a few minutes and subsequently letting the mixture stand atroom temperature, i.e. overnight. The acetonide is then subjected to aJones oxidation (chromic acid in acetone) to provide the 3-ketone.

The 17a,20-isopropylidenedioxy derivative is stable toward basetreatment and elimination of the Sa-hydroxy group is carried out bytreatment with a dilute basic alcohol solution, such .as ethanol ormethanol containing an alkali metal hydroxide such as sodium orpotassium hydroxide. This may be done at room temperature overnight.However, the elimination step also proceeds at refluxing temperaturesfor about 30 minutes to 1 hour using a 0.1 N solution of sodium orpotassium hydroxide in ethanol or methanol.

The thus formed A -3-keto derivative is then alkylated with .an alkylhalide to provide a 4-monoalkyl product or a 4,4-dialky1 product. Aninert solvent such as tert-butanol is employed with the presence ofsodium or potassium tert-alkoxide. The 4,4-dialkylation is achieved bytreatment at 035 C. for about 4 to 20 hours under nitrogen. Increasedyields may be obtained by treating, prior to addition of the alkylatingagent, the acetonide- A -3-ketone with potassium or sodium alkoxide intertbutanol for from 1 to 5 hours under nitrogen, to form a conjugatedanion. The 4-monoalkylation is favored over dialkylation by (a)employing an alkyl chloride rather than the iodide which appears to slowdown the rate of the second alkylation or (b) employing a hightemperature, such as the refluxing temperature of tert.-butanol in whichcase increased steric hindrance of the alkyl group appears to preventthe second alkylation.

The acetonide group is then removed by hydrolysis under acid conditions.This hydrolytic removal of the acetonide group is preferablyaccomplished by refluxing the acetonide in aqueous acetic acid for 2 to3 hours. Other acids such as formic acid may be employed, however.

The thus obtained 17a,20-glycol is then oxidized to a17-hydroxy-20-ketone system by treatment with (a) chromic acid inacetone, with or without the addition of pyridine, (b)N-bromo-succinimide or (c) N-bromoacetamide. The oxidation with chromicacid in acetone is preferably carried out at 0 to 10 C. for one to 3minutes. The other oxidations with N-bromo-suocinimide orN-bromo-acetamide requires the use of an aqueous ormic solvent such asacetone, dioxane or tert.-butanol at mpera-tures of .to 30 C. for 6 to20 hours.

If desired, the 17-hydroxy group may then be acylated. cetylation of the17-hydroxy group may be accomplished treatment with acetic anhydride andp-toluenesulfonic. :id in glacial acetic acid at 10 to 30 C. for 6 to 24ours. Other acylating agents may be employed to pro-- de the particularester desired corresponding to those iters previously set forth.

The invention can be further illustrated by means of 16 followingexamples which are intended as illustrative E the process and productsof the present invention and re not to be construed as limiting theinvention. For urposes of simplicity of illustration, reference is madeerein only to the methyl compounds and acetate esters.

Example 1 Ten grams (10 g.) of a 6B,l6a-dimethylpregnane-8,5u,17a,20-tetrol, M.P. 210212 C., were dissolved 1 350 ml. of acetone,2 ml. of concentrated hydrochloric cid was added and the mixture wasgently boiled for 5 iinutes and then was kept at room temperature for 6hours.

" x52; n0 hydroxy, 5.98, 6.21, 7.90, 8.00, 8.12, 8.26, 8.36

Dilution with water gave crystalline materiaI which was IAnalysis.Calcd. for C H O -C H O: (3:72.76,

1:10.53. Found: C:72.50, H:l0.6l.

Example II Under a nitrogen atmosphere, 10 g. of17a,205-isoropylidenedioxy 68,1611 dimethylpregnane 3 6,5 oc-diOlrepared in Example I, were dissolved in 700 ml. of cetone and cooled to10 C. Then 15 ml. of 8 N hromic acid reagent was added in one portion.After 3 iinutes, a well shaken slurry of 12.5 g. sodium bisulfite 1 20ml. of water was added as quickly as possible. titer the mixture wasstirred for an additional one min- .te, it was poured into 4.0 liters ofwater and the thus ormed crystals were filtered, washed well with waterand ried to give 9.82 g. (99%), M.P. 174-1785 C.,

Two recrystallizations from acetone and n-hexane gave he analyticalsample of 176.,2Og-isopropylidenedioxy-LB,l6a-dimethylpregnane-5a-ol-3-one having M.P. 201.5- 02.5" C., M1 35.2(0.:1, CHCl Analysis.Calcd. for C H O C=74.60, H:10.11. ound: C:74.29,11:10.03.

Example III Nitrogen gas was bubbled into a solution of 9 g. of7a,20-isopropylidenedioxy 65,160. dimethylpregnane- Fa-ol-3-one obtainedin Example II, in 700 ml. of abolute alcohol for 2 minutes. Then ml. of0 .1 N aquelllS sodium hydroxide solution was added and the mixure waskept at room temperature for 18 hours. Then 1.2 m1. of acetic acid wasadded and pH was kept around ieutral. The mixture was concentrated toabout half its *olume by means of a rotary evaporator at about 10-12 nm.Hg. -This solution Was diluted with two liters of vater and extractedwith ethyl acetate. The extracts vere washed, dried, and evaporated togive 6.85 g. 80%), M.P. 153-161 C.,

8.52, 9.11, 9.25, 9.46, 9.61, 9.70, 9.92 and 11.52,.

)P 242 mu, e=16,750, A525, 5.98, 6.21, 7.90, 8.00,

max.

8.12, 8.26, 8.36, 8.52, 9.11, 9.25, 9.46, 9.61, 9.70, 9.92, and 11.52

Analysis.-Calcd. for C H O (3:77.95, H=10.07. Found: (3:78.14, H: 10.09.

Example IV Twelve grams of17a,20g-isopropylidenedioxy-6a,16adimethyl-4-pregnene-3-one weredissolved at room temperature in 360 ml. of tert.-butanol containing 7g. of potassium metal and the mixture was stirred for 5 hours under anitrogen atmosphere. Then 30 ml. of methyl iodide was added and themixture was stirred for 10 minutes at room temperature and then was leftstanding for 16 hours under a nitrogen atmosphere at room ternperaturewithout external cooling or heating. This was diluted with about 300 ml.of water and excess methyl iodide and some tert.-butanol were evaporatedby means of a rotary evaporator (10-12 mm. Hg) for 30 minutes. Afterfurther dilution with water, the product was extracted with ether. Theextracts were washed, dried and evaporated to give 12.31 g. M.P. 144-155C.,

2.87, 5.85, 6.88, 7.22 7, REES? no U.V.

mass spectrum showed stro g parent peak correspon to the molecularweight of 428. Purification by silica gel chromatography (elution with5% ethyl acetate in benzene) gave a compound of M.P. 187-190" C.Recrystallization from n-hexane and acetone gave the analytical sampleof 17a,20g-isopropylidenedioxy-4,4,6, l6a-tetramethyl-S-pre-gnene-3-onehaving M.P. 190191 C., [ab --78.8 (0.:1, CHCl no U.V. absorption,

Analysis.Calcd. for C H O C=78.45, H: 10.35. Found: C:78.22, H:10.32.

Example V 17a,20.-isopropylidenedioxy6a,1fia-dimethyl 4 pregnene-S-one,prepared in Example III, was treated in the same manner described inExample IV, but substituting methyl chloride for methyl iodide to givethe corresponding 17.2,2Og-isopropylidenedioxy 4,6oc,16oz trimethyl 4-pregnene-3-one.

Treatment of 3 g. of 17a,20-isopropylidenedioxy-6a,16a-dimethyl-4-pregnene-3-one in 50 ml. of t-butyl alcohol with aboiling solution of potassium tbutoxide, prepared by dissolving 620 mg.of potassium in 30 ml. of tert.- butyl alcohol, followed by the slowaddition of 2 n11. of methyl iodide and 2 hours reflux also gavel7-a,20-isopropylidenedioxy-4,6a, l 6a-trirnethyl-4-pregnene-3-one.

Example VI max.

LEE; 2.85, 5.88, 6.85, 7.22, 9.00, 9.75, 9.98, 10.23 no U.V. absorption,[a] 41 (c.=l, CHCl Analysis.-Calcd. for C H O C=77.27, H=10.38. Found:C=77.10, 11:10.51.

Similar treatment of the product of Example V gave4,6a,16a-trimethyl-4-pregnene-17a,20-diol 3 one, M.P. 9496 0,

A52; 2.90, 6.01, 6.20;, A21 251 in, Example VII which was identical withthe material obtained in Example VI.

Example VIII A solution of 300 mg. of4,4,6,l6a-tetramethyl-5-pregnene-l7a,20diol-3-one, obtained in ExampleVI, in 40 ml. of acetone was cooled to 10 and dry nitrogen gas wasbubbled in for two minutes and then under a nitrogen atmosphere, 0.3 ml.of 8 N chromic acid reagent was added at once and the mixture wasstirred for three minutes.

A well stirred slurry of 400 mg. of sodium bisulfite in 7 ml. of waterwas added and the mixture was stirred for an additional one minute,poured into ice water and the product extracted with ether to give 285mg. (96% M.P. 177- 180. Recrystallization from n-hexane and acetonefurnished a first crop of 4,4,6,16a-tetramethyl-S-pregnene- 17a-ol-3,20-dione, 208 mg. (70%), M.P. 181-182, [a] 73 (c.=1, CHCl noU.V. absorption,

A 2.87, shoulder at 2.99, 5.95, 6.88, 7.22;;

Mass spectrum agreed with the structure assigned.

Analysis.Calcd. for C H O -H O: C=-74.22, H: 9.96. Found: C=74.27,H=9.85.

Example IX One gram of 4,4,6,l6a-tetramethyl-S-pregnene-l7a,20-diol-3-one, prepared in Example VI, was dissolved in 120 ml. of acetoneand 35 ml. of water, and treated with 2 g. of -N-bromosuccinimide atroom temperature for 17 hours.

Dilution with water gave a crystalline material, which was filtered,washed well with water and dried to give 986 mg., M.P. 91-103 C.,

REE; 2.87, 5.95, 6.88, 7.22;.

no U.V. absorption. Repeated recrystallizations from nhexane and acetonefurnished the pure compound having M.P. of 18-1-182" which was identicalwith the product obtained in Example VIII.

Example X 5.75, 5.85, 8.0l,u, no U.V. absorption 10 Purification bysilica gel chromatography and recrystallization from aqueous methanolgave 820 mg., M.P. 154- 155.5 (3.,

A5,; 5.75, 5.85, and 8.01 no U.V. absorption Analysis.-Calcd. forC27H40O4Z C=75.66, H=9.4l. Found: 0:75.62, H=9.39.

It is to be understood that the invention is not to be limited to theexact details of operation or the exact compounds shown and described asobvious modifications and equivalents will be apparent to those skilledin the art and the invention is to be limited only by the scope of theappended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A steroid compound having the formula CH 20 HJJO CH ---o om where Ais selected from the group consisting of CH3 CH3 K K) O: 116 1'1 no 1%CH CH;

1 2 12 1% and 5 where R and R are alkyl groups having from 1 to 8 5carbon atoms.

2. A steroid compound as defined in claim 1 in which R and R are methyl.

3. A steroid compound of the formula ]t(Jo C o11 H C 3 ---0 CH p no itwhere R is an alkyl group having from 1 to 8 carbon atoms. 4. A steroidcompound of the formula 3 ---o \CH3 HO R vhere R is an alkyl grouphaving from 1 ltOl'IlS.

5. A steroid compound of the formula vhere R is an alkyl group havingfrom 1 items.

6. A steroid compound of the formula to 8 carbon to 8 carbon vhere R andR are alkyl groups having from' 1 to 8 :arbon atoms.

7. A steroid compound of the formula --OH i In where R and R are alkylgroups having from 1 to 8 :arbon atoms.

8. A steroid compound having the formula where B is selected from thegroup consisting of and 0 where R and R are alkyl groups having from 1to 8 carbon atoms.

11. In a process of preparing a compound selected from the groupconsisting of and where B is selected from the group consisting of and I13' R and R are alkyl groups having from 1 to 8 carbon atoms and R isselected from the group consisting of alkyl, cycloalkyl, aralkyl andalkoxyaralkyl groups in which the alkyl group has from 1 to 12 carbonatoms in which the alkyl group has from '1 to 8 carbon atoms therebyproviding with chromic acid thereby oxidizing the 3-hydroxyl 40 group toa 3-ketone group providing where R is as previously defined,

(c) treating the product of (b) with an alcoholic solution of an alkalimetal hydroxide thereby eliminating the 5a-hydroxy group and providingwhere R is as previously defined,

(d) treating the product of (c) with an alkyl halide 75 and the acylgroup isphenyl, the sequence of steps com- 5 H 0 a prising H3O (a)heating in the presence of hydrochloric acid an ---0 CH3 acetonesolution of T EH: H -OH B mo I l --R where B is selected from the groupconsisting of 1130 I H30 1 HO 5 0% I I HO R B1 II thereby providing CH3Y HCO OHQ -o \CHQ I R R1 R R Hie i and R and R are alkyl groups havingfrom 1 to 8 carbon atoms, (e) hydrolyzing the product of (d) under acidcondi- I tions, said acid being selected from the group con- I sistingof acetic and formic acids, thereby providing HO R (EH3 where R is aspreviously defined, HCFOH (b) treating an acetone solution of theproduct of (8.) H3O where B and R are as previously defined and (f)treating the product of (e) with an oxidizing agent selected from thegroup consisting of chromic acid, N-bromo-succinimide andN-bromo-acetamide thereby oxidizing the 17a,20;8-glycol to a17ot-hydroxywhere B and R are as previously defined. 12. A process asdefined in claim 11 in which R and R are methyl.

13. A process of preparing 15 p 16 where B is'se'lected from the groupconsisting of a CH3 CH3 H -on H3O R R I:

B l tlid 10 where B and R are as previously defined. 14. A process asdefined in claim 13 in which R and I p R are methyl.

V I 15 References Cited by the Examiner O: Graber et 211.: Journal Org.Chem. (1962), vol. 27,

pages 2534-2541 relied on.

Tschesche et aL: Ann. Chem., vol. 199 (1961), page and R and R are alkylgroups having from 1 to 8 carbon 642 e ied 0 ltOIl'lS, comprisingtreating with chromic acid in acetone 20 l 17 20 1 fth f r ul LEWISGOTTS, Primary Exammer.

UNITED STATES PATENT OFFICE V CERTIFICATE OF CORRECTION W993 Patent No.3 210 ,342 October 5, 1965 Robert P. Graber et al It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below.

Column 1, line 15, for "derivates" read derivatives line 25, for"dysmennorhoes" read dysmennorhoea columns l and 2 formula [I] andcolumn 3 formula [VI (a) for that portion of the formula, eachoccurrence, reading H (|I read H column 2 formula [IV] and columns 3 and4 formula [V(b) for the upper left-hand portion of the formula, eachoccurrence, reading CH read CH columns 3 and 4 formulas [V(b) [VI (b)][VII (b]] and [VIII (b)] for the lower left-hand portion of the formula,each occurrence, reading same columns 3 and 4,'formula [VIII(b)] for theupper righthand portion of the formula reading 0 read A column 5, lines50 to 56, the lower right-hand portion of the formula reading 1 R read Rcolumn 8, line 67, for "were" read was column 11, lines 16 to 27, forthe lower left-hand portion of the formula reading read R column 12,lines 11 to 17, and column 15, lines 2 to 9, the formula, eachoccurrence, should appear as shown below instead of as in the patent:

Signed and sealed this 13th day of September 1966.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. A STEROID COMPOUND HAVING THE FORMULA